IEEE Transactions on Automatic Control, Vol.41, No.3, 379-392, 1996
J-Inner-Outer Factorization, J-Spectral Factorization, and Robust-Control for Nonlinear-Systems
The problem of expressing a given nonlinear state-space system as the cascade connection of a lossless system and a stable, minimum-phase system (inner-outer factorization) is solved for the case of a stable system having state-space equations affine in the inputs, The solution is given in terms of the stabilizing solution of a certain Hamilton-Jacobi equation, The stable, minimum-phase factor is obtained as the solution of an associated nonlinear spectral factorization problem, As an application, one can arrive at the solution of the nonlinear H-infinity-control problem for the disturbance feedforward case.